The present invention relates to the structure of a foldable electronic apparatus and, more particularly, to a hinge mechanism for a hand-held radio communication apparatus.
A hand-held radio communication apparatus, e.g., a hand-held mobile telephone is one of portable electronic apparatuses extensively used today. For miniaturization, it is a common practice with such a hand-held radio communication apparatus to divide the casing thereof into two and connect the two casing parts by a hinge mechanism. In this configuration, the casing parts are rotatable about the hinge mechanism toward and away from each other, i.e., the apparatus is foldable. The casing parts are locked in a position where they are spaced apart by a predetermined angle by lugs and recesses included in the hinge mechanism. To unlock the casing parts, a force greater than the bias of a spring also included in the hinge mechanism is exerted on the casing parts. The prerequisite with such a mechanism is that the bias of the spring be greater than the predetermined force associated with the predetermined angle, so that the mechanism may rotate beyond the predetermined angle only when a force greater than the predetermined force acts thereon. This brings about a problem that the apparatus cannot be folded or unfolded from or to the predetermined angle unless a force overcoming the bias of the spring is exerted. Should use be made of a spring exerting a relatively small bias to eliminate the above problem, the casing parts locked at the predetermined angle would be easily unlocked by a small effort.